Custom Norton MK3 Commando Wiring Diagram – Graham Tiller

Grant Tiller

This is a custom wiring diagram for Graham Tiller – MY DAD 🙂

We have fitted a Tri-Spark electronic ignition to his bike.

Grant Tiller

We also fitted a 3 phase Lucas alternator – a nice choice for superior charging in modern traffic conditions.

Grant Tiller

We also fitted the superb Shindengen SH775 regulator/rectifier – it’s the only way i’d ever dream of fitting a lithium-based battery to a bike.

Grant Tiller

Talking of batteries, we went large!

We fitted a Shorai LFX36L3-BS12 (note this is a pre-MK3 battery tray, so the battery runs along the bike, not across it)

It is 36 Ah (or the lead acid equivalent) – but more importantly it has 540CCA (cold cranking amps)

It turns the engine over like the plugs aren’t in it!

Grant Tiller

We also fitted Colorado Norton Works handlebar switches (modified Honda units) because we fitted a Brembo brake master cylinder and ‘matching’ Magura clutch lever so were no longer bound to the original switchgear.

Grant Tiller
Grant Tiller

In lieu of the twin 6 volt coils, We have gone with the dual output single tower coil from Colorado Norton Works (it’s the brilliant Crane Cams unit) and looks much neater.

Grant Tiller

The final thing worth noting is the Charge Warning Light.

Grant Tiller

The nice thing about the Improving Classic Motorcycles unit is that you can retain the original warning light – so it looks totally factory.

It gives you a lot more useful information about the state of the battery and charging system compared to the standard assimilator unit, which looks for AC output from the alternator stator only.

Grant Tiller

Here’s the bike basking in the sunshine!

Grant Tiller

Here is the Wiring Diagram for Graham’s bike.

Custom Norton MK3 Commando Wiring Diagram – Graham Tiller PNG 3066×1841

Grant Tiller

8 replies

    • I see charge voltage top out at 14.8 volts DC with the Shindengen.
      At very low RPMs, the lowest I have seen is 14.5 volts.

      Personally I would prefer to see the peak voltage set a little lower than it is on the SH775 – but it was not designed specifically for lithium-based batteries, and this really is the best I have found so far.

      • Grant, actually, for a LiFe battery, those are great charging voltages. While a lead acid battery is considered fully charged with a resting voltage between 12.8 volts and 13.2 volts [ideal], LiFe batteries take more voltage. I would suggest you visit Shorai’s FAQ page, linked below.

        https://shoraipower.com/faq

        Open the “Can I Use Lead-Acid Battery Chargers or Charger/Tenders? question. View the battery charge level chart.

        • Yes, I have an ok understanding of battery chemistry.

          The absolute peak charge voltage for a LiFEPO4 cell is 4.2 volts per cell (so 16.8 volts for an automotive battery)
          At that point, the cells start to become damaged and life of the battery is degraded.

          In my opinion, I would only want to charge at anything approaching an upper rate on a per cell basis, and on the grounds that no regulator/rectifier interfaces with a charge balance port on the battery itself addressing charge rate on a per cell basis (like the manufacturers dedicated chargers do)
          For me, personally, I am much more comfortable sticking with the lower charge rate as far as what the reg/rec puts out.

          There are some exceptions to this – batteries like the EarthX ones that contain a charge circuit built into the battery casing itself that will address the individual cell requirements and make sure that charging is balanced.
          These are superb batteries, but you pay for the privilege, and I would suggest these are not the off the shelf batteries people are buying to put in their bikes.

          – EarthX specify 14.6 volts as the absolute maximum charging voltage, even with their clever BMS circuitry (battery management system)
          – Shorai is 14.6 volts
          – Antigravity is 14.7 volts
          – Ballistic is 14.4 volts
          – Skyrich is 15 volts
          – Shido is 15 volts (they have a built in BMS)
          – Western Power Fire Power Featherweight is 15 volts

          Personally, I would feel most comfortable if the charge voltage threshold was capped at 13.8 volts when Lithium-based batteries are concerned.

          …I am still searching for that perfect series-type MOSFET reg/rec that charges at 13.8 volts. But haven’t found one yet!

  1. The Shorei battery you are using would never fit in a Mk III battery tray/air box configuration. You should have mentioned that you replaced the stock battery tray with an earlier 750/850 battery tray. I like the chrome battery tray! Without a LiFe battery, that would be cosmetic suicide [leaking acid] Thanks for your great web site.

    • This site tends to focus on the electrical side, so I haven’t gone into any detail on any of the other stuff we’ve done.

      The MK3 has been subtly modified quite a bit in addition to the electrical changes:
      – Corbin seat
      – moved front brake from left front to right back
      – 18” rear wheel
      – pre-MK3 ham can air filter
      – pre-MK3 stainless steel battery tray
      – stainless braided lines
      – 13mm brake master cylinder
      – drilled discs (not shown in the picture)

      I’m glad you like the site – hopefully there is something here of use to you!

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